Method for fabricating single-damascene structure, dual damascene structure, and opening thereof

ABSTRACT

A method for fabricating a single-damascene opening is described. The method includes providing a substrate having a conductive line formed therein. A barrier layer, a dielectric layer, a metal hard mask layer, a silicon oxynitride layer, a bottom antireflection layer and a patterned photoresist layer are sequentially formed on the substrate. The bottom antireflection layer, the silicon oxynitride layer and the metal hard mask layer that are not covered by the patterned photoresist layer are removed in a single process step, until a part of the surface of the dielectric layer is exposed. Thereafter, the patterned photoresist layer and the bottom antireflection layer are removed. Further using the silicon oxynitride layer and the metal hard mask layer as a mask, a portion of the dielectric layer and a portion of the barrier layer are removed to form a damascene opening that exposes the surface of the conductive line.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for fabricating an interconnect structure and an interconnect opening. More particularly, the present invention relates to a method for fabricating a single-damascene structure, a dual-damascene structure, and an opening thereof.

2. Description of Related Art

With the advancement of semiconductor technologies, the dimensions of semiconductor devices continuously reduce to the deep sub-micron territory. As the level of integration of integrated circuits increases, the surface of a chip is inadequate to accommodate all the required interconnects. In order to accommodate the increase of interconnects after the miniaturization of semiconductor devices, the design of a multilevel interconnect is used in ultra large scale integration circuits (ULSI).

In general, the multilevel interconnection is formed using a damascene process, which includes the single-damascene process or the dual-damascene process. Currently, the damascene process that involves the defining of a trench (or opening) in a dielectric layer requires forming a titanium nitride layer on the dielectric layer first. Thereafter, a photoresist layer with a trench (or opening) pattern is formed over the titanium nitride layer. The trench (or opening) pattern of the photoresist layer is then transferred to the titanium nitride layer. Further using the titanium nitride layer with the trench (or opening) pattern as a hark mask, a trench (or opening) is then defined in the dielectric layer. Limited by the yellow light process, a plasma-enhanced oxide (PE-oxide) layer is typically formed on the titanium nitride layer to increase the process window, wherein both the titanium nitride layer and the PE-oxide layer serve as the hard mask layer in the damascene process.

However, there are problems still needed to be resolved in a damascene process. For example, before defining the trench (or opening) in the dielectric layer, two etching steps are performed in order to define the trench (or opening) pattern in the hard mask layer. The two etching steps include a first etching step and a second etching step. The first etching step includes removing a portion of the PE-oxide layer until the surface of the titanium nitride layer is exposed using the photoresist layer as a mask. The second etching step includes etching a portion of the titanium nitride layer until the surface of the dielectric layer is exposed. Accordingly, the conventional damascene process requires performing multiple steps, and thus a longer cycle time is resulted.

SUMMARY OF THE INVENTION

Accordingly, the present invention at least provides a method for fabricating a single-damascene opening, in which the process step is simplified and the cycle time is conserved.

The present invention also provides a single-damascene structure, in which the process step is simplified and the cycle time is conserved.

The present invention further provides a method for fabricating a dual-damascene opening, in which the process step is simplified and the cycle time is conserved.

The present invention further provides a dual-damascene structure, in which the process step is simplified and the cycle time is conserved.

The present invention provides a fabrication method of a single-damascene opening. The method includes providing a substrate having a conductive line already formed therein. Thereafter, a barrier layer, a dielectric layer, a metal hard mask layer, a silicon oxynitride layer, a bottom antireflection layer and a patterned photoresist layer are sequentially formed on the substrate. The bottom antireflection layer, the silicon oxynitride layer and the metal hard mask layer that are not covered by the patterned photoresist layer are removed until a part of the surface of the dielectric layer is exposed. The patterned photoresist layer and the bottom antireflection layer are then removed. Further using the silicon oxynitride layer and the metal hard mask layer as a mask, a portion of the dielectric layer and a portion of the photoresist layer are removed to form a damascene opening that exposes the surface of a conductive line.

According to one embodiment of the present invention, in the fabrication method of the above-mentioned single-damascene opening, a silicon oxide layer can further form after the formation of the silicon oxynitride layer and before the formation of the bottom antireflection layer. In another embodiment, a surface property alteration process can be conducted on the silicon oxynitride layer to form an oxide layer on the silicon oxynitride layer. The surface property alteration process includes a plasma process using an oxygen containing gas. According to one embodiment of the present invention, in the above fabrication method of a single-damascene opening, the material of the conductive line is copper, for example. Further, the material of the metal hard mask layer includes, but not limited to, tantalum, tantalum nitride, titanium, titanium nitride, tungsten or tungsten nitride. The material of the dielectric layer is a low dielectric constant material, for example.

The present invention provides a single-damascene structure, wherein the single-damascene structure includes a substrate, a barrier layer, a dielectric layer, a metal hard mask layer, a silicon oxynitride layer and a conductive layer. A conductive line is disposed in the substrate. The barrier layer is positioned on the substrate, while the dielectric layer is positioned on the barrier layer. The metal hard mask layer is disposed on the dielectric layer, and the silicon oxynitride layer is disposed on the metal hard mask layer. A single-damascene opening that exposes a part of the conductive line is configured in the silicon oxynitride layer, the metal hard mask layer, the dielectric layer and the barrier layer. A conductive layer is disposed in the damascene opening.

According to one embodiment of the present invention, a silicon oxide layer is also disposed on the silicon oxynitride layer in the above single damascene structure. In another embodiment, an oxide layer is also disposed on the silicon oxynitride layer.

According to one embodiment of the present invention, the material of the dielectric layer in the single-damascene structure is a low dielectric constant material, for example. The material of the hard mask includes, but not limited to, tantalum, tantalum nitride, titanium, titanium nitride, tungsten or tungsten nitride. The material of the conductive line includes copper, for example.

The present invention provides a method for fabricating a dual-damascene opening. The method includes providing a substrate having a conductive line already formed therein. A barrier layer, a dielectric layer, a metal hard mask layer, a silicon oxynitride layer, a first bottom antireflection layer and a first patterned photoresist layer are sequentially formed on the substrate. The first bottom antireflection layer, the silicon oxynitride layer and the metal hard mask layer that are not covered by the first patterned photoresist layer are removed to form a first opening that exposes a part of the surface of the dielectric layer. Thereafter, a second patterned photoresist layer is formed on the substrate to cover the silicon oxynitride layer and a part of the dielectric layer. Further using the second patterned photoresist layer as a mask, a portion of the dielectric layer is removed to form a second opening in the dielectric layer. The second patterned photoresist layer is then removed. After this, a portion of the dielectric layer and a portion of the barrier layer are removed to form a dual-damascene opening that exposes the surface of the conductive line using the silicon oxynitride layer and the metal hard mask layer as a mask.

According to one embodiment of the present invention, the above fabrication method of a dual-damascene opening can further include forming a silicon oxide layer after the silicon oxynitride layer is formed and before the bottom antireflection layer is formed.

According to one embodiment of the present invention, in the above fabrication method of a dual-damascene opening, the material of the conductive line is copper, for example. Further, the material of the metal hard mask layer includes, but not limited to, tantalum, tantalum nitride, titanium, titanium nitride, tungsten or tungsten nitride. The material of the dielectric layer is a low dielectric constant material, for example.

The present invention provides a dual-damascene structure, wherein the dual-damascene structure includes a substrate, a barrier layer, a dielectric layer, a metal hard mask layer, a silicon oxynitride layer and a conductive layer. A conductive line is disposed in the substrate. The barrier layer is positioned on the substrate, while the dielectric layer is positioned on the barrier layer. The metal hard mask layer is disposed on the dielectric layer, and the silicon oxynitride layer is disposed on the metal hard mask layer. A dual-damascene opening that exposes a part of the conductive line is configured in the silicon oxynitride layer, the metal hard mask layer, the dielectric layer and the barrier layer. A conductive layer is disposed in the dual-damascene opening.

According to one embodiment of the present invention, in the above dual-damascene structure, a silicon oxide layer can also be disposed on the silicon oxynitride layer. In another embodiment, an oxide layer can also be disposed on the silicon oxynitride layer.

According to one embodiment of the present invention, the material of the dielectric layer in the dual-damascene structure is a low dielectric constant material, for example. The material of the hard mask includes, but not limited to, tantalum, tantalum nitride, titanium, titanium nitride, tungsten or tungsten nitride. The material of the conductive line includes copper, for example.

According to the fabrication method and the damascene structure of the present invention, the plasma enhanced oxide layer (PE-oxide) in the prior art is replaced by the silicon oxynitride layer. Moreover, before the step of defining the trench in the dielectric layer, only a single etching step is required to define the trench (or opening) pattern in the hard mask layer. Therefore, the process step of the fabrication method of the present invention is simplified and the cycle time is reduced.

Several exemplary embodiments of the invention will now be described in detail with reference to the accompanying drawings. It is to be understood that the foregoing general description and the following detailed description of preferred purposes, features, and merits are exemplary and explanatory towards the principles of the invention only and are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIGS. 1A to 1D are schematic diagrams showing the method for fabricating a single-damascene opening according to one embodiment of the present invention.

FIGS. 2A to 2G are schematic diagrams showing the method for fabricating a dual-damascene opening according to one embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the present preferred embodiments of the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.

FIGS. 1A to 1D are schematic diagrams showing the method for fabricating a single-damascene opening according to one embodiment of the present invention.

Referring to FIG. 1A, a substrate 100 is provided, wherein a conductive line 102 is already formed in the substrate 100. The conductive line 102 is formed with copper, for example.

Still referring to FIG. 1A, a barrier layer 104, a dielectric layer 106, a metal hard mask layer 108, a silicon oxynitride layer 110, a bottom antireflection layer 112 and a patterned photoresist layer 114 are sequentially formed on the substrate 100.

The material of the photoresist layer 114 includes silicon nitride or other suitable materials. The photoresist layer 114 is formed by chemical vapor deposition, for example. The barrier layer 104 serves to prevent the oxidation of the copper surface and the diffusion of copper to the dielectric layer 106. The dielectric layer 106 is, for example, a low dielectric constant dielectric layer which is formed with a low dielectric constant material including inorganic materials, such as hydrogen silsesquioxane (HSQ), fluronated silicon glass (FSG), etc., or organic materials, such as fluorinated poly(arylene ether) (Flare), aromatic hydrocarbons (SILK), poly-arylethers (parylene), etc. The dielectric layer 106 is formed by chemical vapor deposition, for example. In one embodiment, the dielectric layer 106 is constituted with a low dielectric constant dielectric layer and an insulation layer, wherein the insulation layer can also serve as a chemical mechanical polishing (CMP) stop layer to prevent the dielectric layer 106 from being polished during the CMP process. The material of the metal hard mask layer 108 includes tantalum, tantalum nitride, titanium, titanium nitride, tungsten or tungsten nitride, and the metal hard mask layer 108 is formed by chemical vapor deposition. The bottom antireflection layer is an organic bottom antireflection layer or inorganic bottom antireflection layer. The inorganic antireflection layer is formed by chemical vapor deposition, for example. The material of the inorganic antireflection layer includes, but not limited to, a non-crystalline phase carbon film, silicon nitride, silicon oxynitride or titanium nitride, etc.

In one embodiment, after forming the silicon oxynitride layer 110 and before forming the bottom antireflection layer 112, a silicon oxide layer (not shown) can also form on the silicon oxynitride layer 110 so that the refractive index (n) and the dielectric constant (k) of the silicon oxynitride layer 110 remain unchanged over time.

In another embodiment, after forming the silicon oxynitride layer 110, and before forming the bottom antireflection layer 112, a surface property alteration process can perform on the silicon oxynitride layer 110 to form an oxide layer (not shown) on the silicon oxynitride layer 110 in order to maintain the refractive index and the dielectric constant of the silicon oxynitride layer 110 from varying over time. The surface property alteration process includes a plasma process using an oxygen containing gas.

More particularly, the silicon oxynitride layer 110 can reduce the reflective light of the underlying reflective material (metal hard mask layer 108). Consequently, the photolithograph process is improved.

Referring to FIG. 1B, the bottom antireflection layer 112, the silicon oxynitride layer 110 and the metal hard mask layer 108 that are not covered by the patterned photoresist layer 114 are directly removed until a part of the surface of the dielectric layer 106 is exposed. In other words, the removal of the bottom antireflection layer 112, the silicon oxynitride layer 110 and the metal hard mask layer 108 that are not covered by the patterned photoresist layer 114 is completed by performing one etching process. In essence, only a single etching process is performed.

Continuing to FIG. 1C, the patterned photoresist layer 114 and the bottom antireflection layer 112 are removed, for example, by an etching process. Thereafter, the silicon oxynitride layer 110 and the metal hard mask layer 108 are used as a mask to remove a portion of the dielectric layer 106 and a portion of the barrier layer 104 to form a damascene opening 116 that exposes the surface of the conductive line 102. Removing the portion of the dielectric layer and the portion of the barrier layer is accomplished by removing the dielectric layer that is not covered by the silicon oxynitride layer 110 and the metal hard mask layer 108. The dielectric layer 106 is removed by, for example, performing an etching process. Thereafter, the exposed barrier layer 104 is removed, for example, by an etching process.

After this, as shown in FIG. 1D, the damascene opening 116 is filled with a conductive layer 118. Further using the CMP process to remove the excess metal, a single-damascene structure is formed. The material of the conductive layer 118 is metal or polysilicon, for example.

It is worthy to note that before the step of defining an opening in the dielectric layer, only a single etching step is performed to define the opening in the hard mask layer. Therefore, not only the process step is simplified, the cycle time is greatly conserved.

The single-damascene structure formed according the method of the fabrication is disclosed as follows. Since the materials of the parts of the damascene structure have been disclosed in the above embodiment, they will not be reiterated herein.

Still referring to FIG. 1D, the single-damascene structure includes the substrate 100, the barrier layer 104, the dielectric layer 106, the metal hard mask layer 108, the silicon oxynitride layer 110 and the conductive layer 119. The conductive line 102 is disposed in the substrate 100. The barrier layer 104 is disposed on the substrate 100, and the dielectric layer 106 is disposed on the barrier layer 104. The metal hard mask layer 108 is disposed on the dielectric layer 106, and the silicon oxynitride layer 110 is disposed on the metal hard mask layer 108. The damascene opening 116 exposing a part of the surface of the conductive line 102 is configured in the silicon oxynitride layer 110, the metal hard mask layer 108, the dielectric layer 106 and the barrier layer 104. The conductive layer 118 is disposed in the damascene opening 116.

In one embodiment, single-damascene structure further can include a silicon oxide layer (not shown), disposed on the silicon oxynitride layer 112.

In another embodiment, the single-damascene structure can include an oxide layer (not shown), disposed on the silicon oxynitride layer 112. The oxide layer is formed by performing a plasma process on the silicon oxynitride layer 112 to alter the surface property of silicon oxynitride layer 112. The above silicon oxide layer and oxide layer can serve to maintain the refractive index and the dielectric constant of the silicon oxynitride layer from changing over time.

FIGS. 2A to 2G are schematic diagrams showing the method for fabricating a dual-damascene opening according to one embodiment of the present invention. The same reference numbers are used in FIGS. 1A to 1D and FIGS. 2A to 2G to refer to the same or like parts.

Referring to FIG. 2A, a substrate 100 is provided, wherein a conductive line 102 is already formed in the substrate 100. The conductive line 102 is formed with copper, for example.

Still referring to FIG. 2A, a barrier layer 104, a dielectric layer 106, a metal hard mask layer 108, a silicon oxynitride layer 110, a bottom antireflection layer 112 and a patterned photoresist layer 114 are sequentially formed on the substrate 100.

In one embodiment, after forming the silicon oxynitride layer 110 and before forming the bottom antireflection layer 112, a silicon oxide layer (not shown) can also form on the silicon oxynitride layer 110 so that the refractive index (n) and the dielectric constant (k) of the silicon oxynitride layer 110 remain unchanged over time.

In another embodiment, after forming the silicon oxynitride layer 110, and before forming the bottom antireflection layer 112, a surface property alteration process is performed on the silicon oxynitride layer 110 to form an oxide layer (not shown) on the silicon oxynitride layer 110 in order to maintain the refractive index and the dielectric constant of the silicon oxynitride layer 110 from changing over time. The surface property alteration process includes a plasma process using an oxygen containing gas.

As shown in FIG. 2B, the bottom antireflection layer 112, the silicon oxynitride layer 112 and the metal hard mask layer 108 not covered by the patterned photoresist layer 114 are removed in a single process step to form a trench 120 that exposes the surface of a part of the dielectric layer 106.

Similarly, the silicon oxynitride layer 110 and the metal hard mask layer 108 are removed under the same etching condition. Therefore, unlike the conventional practice in which the metal hard mask layer and the overlying layer have different properties and are removed under different etching conditions, the process step of the present invention is greatly simplified and the cycle time is conserved to increase the yield.

Thereafter, as shown in FIG. 2C, the patterned photoresist layer 114 and the bottom antireflection layer 112 are removed. A patterned photoresist layer 122 is then formed over the substrate 100 to cover the silicon oxynitride layer 110 and a part of the dielectric layer 106. This patterned photoresist layer 122 has an opening pattern 123 therein.

In one embodiment, before forming the patterned photoresist layer 122, a bottom antireflection layer (not shown) is formed over the substrate 100 to cover the silicon oxynitride layer 110 and the dielectric layer 106.

Referring to FIG. 2D, using the patterned photoresist layer 122 as a mask, a portion of the dielectric layer 106 is removed to form an opening 124 in the dielectric layer 106.

Continuing to FIG. 2E, the patterned photoresist layer 122 is removed, for example, by performing an etching process.

Thereafter, as shown in FIG. 2F, the silicon oxynitride layer 110 and the metal hard mask layer 108 are used as a mask, and a portion of the dielectric layer 106 and a portion of the barrier layer 104 are removed until the surface of the conductive line 102 is exposed to form a trench 121 and an opening 125. The trench 121 and the opening 125 serve as a dual-damascene opening 126.

Continuing to FIG. 2G, the dual-damascene opening 126 is filled with a conductive layer 128. Further using a CMP process to remove the excess metal, a conductive line is formed in the trench 121 and a plug is formed in the opening 125, wherein the conductive line and the plug constitute a dual damascene structure. The material of the conductive layer 128 includes, but not limited to, a metal material or polysilicon.

The dual-damascene structure formed according the fabrication method of the present invention is disclosed as follows. Since the materials for the parts of the damascene structure have been disclosed in the above embodiment, they will not be reiterated herein.

Referring again to FIG. 2G, the dual-damascene structure mainly includes the substrate 100, the barrier layer 104, the dielectric layer 106, the metal hard mask layer 108, the silicon oxynitride layer 110 and the conductive layer 128. The conductive line 102 is configured in the substrate 100. The barrier layer 104 is disposed on the substrate 100, and the dielectric layer 106 is disposed on the barrier layer 104. The metal hard mask layer 108 is disposed on the dielectric layer 106. The silicon oxynitride layer 110 is disposed on the metal hard mask layer 108. The dual-damascene opening 126 exposing a part of the surface of the conductive line 102 is configured in the silicon oxynitride layer 110, the metal hard mask layer 108 and the dielectric layer 106. The conductive layer 128 is disposed in the damascene opening 126.

In one embodiment, the dual-damascene structure further includes a silicon oxide layer (not shown), disposed on the silicon oxynitride layer 112.

In another embodiment, the dual-damascene structure includes an oxide layer (not shown), disposed on the silicon oxynitride layer 112. The oxide layer is formed by performing a plasma process on the silicon oxynitride layer 112 to alter the surface property of the silicon oxynitride layer 112. The above silicon oxide layer and oxide layer serve to maintain the refractive index and the dielectric constant of the silicon oxynitride layer from altering over time.

According to the present invention, before defining a trench (or opening) in the dielectric layer, only a single etching step is performed to define a trench (or opening) pattern in the hard mask layer. Not only the process step is simplified, the cycle time is conserved. Further, the silicon oxynitride layer can absorb the reflective light from the metal mask layer to enhance the photolithograph process.

It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents. 

1. A fabrication method of a single-damascene opening, the method comprising: providing a substrate, wherein a conductive line is already formed in the substrate; forming sequentially a barrier layer, a dielectric layer, a metal hard mask layer, a silicon oxynitride layer, a bottom antireflection layer and a patterned photoresist layer on the substrate, wherein after forming the silicon oxynitride layer and before forming the bottom antireflection layer, a surface property alteration process is performed on the silicon oxynitride layer to form an oxide layer on the silicon oxynitride layer; removing the bottom antireflection layer, the silicon oxynitride layer and the metal hard mask layer that are not covered by the patterned photoresist layer in a single process step until a part of a surface of the dielectric layer is exposed; removing the patterned photoresist layer and the bottom antireflection layer; and removing a portion of the dielectric layer and a portion of the barrier layer to form a damascene opening that exposes a surface of the conductive line using the silicon oxynitride layer and the metal hard mask layer as a mask.
 2. The method of claim 1, wherein after forming the silicon oxynitride layer and before forming the bottom antireflection layer, a silicon oxide layer is formed on the silicon oxynitride layer.
 3. The method of claim 1, wherein the surface property alteration process comprises a plasma process using an oxygen containing gas.
 4. The method of claim 1, wherein the metal hard mask layer is formed with a material selected from the group consisting of tantalum, tantalum nitride, titanium, titanium nitride, tungsten and tungsten nitride.
 5. The method of claim 1, wherein the dielectric layer is formed with a material comprising a low dielectric constant material.
 6. The method of claim 1, wherein the conductive line is formed with a material comprising copper.
 7. A method for fabricating a dual damascene opening, the method comprising: providing a substrate, wherein a conductive line is already formed in the substrate; forming sequentially a barrier layer, a dielectric layer, a metal hard mask layer, a silicon oxynitride layer, a first bottom antireflection layer and a first patterned photoresist layer on the substrate, wherein after forming the silicon oxynitride layer and before forming the first bottom antireflection layer, a surface property alteration process is performed on the silicon oxynitride layer to form an oxide layer on the silicon oxynitride layer; removing the first bottom antireflection layer, the silicon oxynitride layer and the metal hard mask layer that are not covered by the first patterned photoresist layer in a single process step to form a first opening that exposes a part of a surface of the dielectric layer; removing the patterned photoresist layer and the bottom antireflection layer; forming a second patterned photoresist layer over the substrate to cover the silicon oxynitrde layer and a first part of the dielectric layer; removing an exposed part of the dielectric layer to form a second opening in the dielectric layer using the second patterned photoresist layer as a mask; removing the second patterned photoresist layer; and removing a part of the barrier layer and a second part of the dielectric layer to form a dual damascene opening that exposes a surface of the conductive line.
 8. The method of claim 7, wherein after forming the silicon oxynitride layer and before forming the first bottom antireflection layer, a silicon oxide layer is further formed on the silicon oxynitride layer.
 9. The method of claim 7, wherein the surface property alteration process further comprises a plasma process using an oxygen containing gas.
 10. The method of claim 7, wherein before forming the second patterned photoresist layer, a second bottom antireflection layer is further formed on the substrate, wherein the second bottom antireflection layer fills the first opening and covers the silicon oxynitride layer.
 11. The method of claim 7, wherein the metal hard mask layer is formed with a material selected from the group consisting of tantalum, tantalum nitride, titanium, titanium nitride, tungsten and tungsten nitride.
 12. The method of claim 7, wherein the dielectric layer is formed with a material comprising a low dielectric constant material.
 13. The method of claim 7, wherein the conductive line is formed with a material comprising copper. 